This invention relates to plier-type hand tools having a double toggle actuating linkage. The disclosed embodiment is particularly directed to the achievement of a tool for installing a multi-contact electrical connector on a flat conductor cable although other uses for the invention will be apparent from the following description. Tools having toggle mechanisms are shown, for example, in U.S. Pat. Nos. 2,327,368; 2,436,497; 2,464,472 and 1,362,595.
U.S. Pat. No. 3,820,055 discloses and claims a multi-contact electrical connector which is installed on a flat conductor cable by simply locating the cable adjacent to a cable-receiving surface of the connector housing and moving the cable normally of its plane towards that surface. Contact terminals extend from the cable-receiving surface and these terminals penetrate the cable and establish electrical contact with the conductors upon such movement of the cable.
Connectors of the type shown in U.S. Pat. No. 3,820,055 are now being manufactured with 50 and more contact terminals extending from the cable-receiving surface for engagement with the 50 conductors of the cable. When this number of conductors and terminals is involved, a relatively high force is required to install the connector on the cable and the installation process must be carried out with a high degree of precision and control if a satisfactory installation is to result. While there are a vast number of plier-type hand tools commercially available, and many more have been proposed in prior publications, such as the U.S. Patents cited above, there is apparently no suitable hand tool for connector installing operations of the type under consideration. In general, most hand tools are designed such that they are incapable of accommodating a relatively wide (3 inches or more) cable between their jaws. Furthermore, most types of hand tools, if modified for connector-cable installation processes, would tend to undergo elastic deflection when the connector is installed on the cable because of the high stresses developed and the deflection, in turn, would result in non-uniform application of forces on the cable and connector which would, in turn, lead to unsatisfactory installation.
I have developed a plier-type hand tool having parallel jaws and a reciprocable ram in one of the jaws which is movable towards the outer jaw. The ram is reciprocated by a removable handle which, upon movement thereof, straightens two toggle mechanisms to drive the ram along its working stroke. The arrangement of the toggle mechanisms is such that a high thrust or force is developed in the ram, a thrust which is more than adequate to install a relatively high count flat cable on a connector. The toggle arrangement is also such that a deep throat is provided in the tool and a relatively wide flat cable can be accommodated between the jaws of the tool. Finally, a removable tension member extends between the ends of the jaws so that excessive deflection of the tool (as a result of high localized stresses) is avoided.
It is accordingly an object of the invention to provide an improved plier-type hand tool. A further object is to provide a hand tool capable of being used on a relatively large workpiece such as a relatively wide multi-conductor cable. A further object is to provide a hand tool which is not subject to excessive elastic deflection when put to use. A further object is to provide plier-type hand tool which is convenient to use by a person of average strength and which is capable of developing a high force or thrust.